Near degenerate rearrangement between the radical cations of formaldehyde and hydroxymethylene
Motivated by the recent experiments of Berkowitz, a systematic theoretical study of the ion isomerization H/sub 2/CO/sup +/..-->..HCOH/sup +/ has been carried out. Structures and vibrational frequencies for H/sub 2/CO/sup +/, the transition state, and the cis and trans isomers of HCOH/sup +/ have been determined at the double zeta basis set self-consistent-field (SCF) level of theory. Equilibrium geometries were also predicted from SCF theory using a double zeta plus polarization (DZ+P) basis set. Final energetics were pinned down using DZ+P configuration interaction, involving a total of 16 290 configurations. The most reliable theoretical results suggest that trans-HCOH/sup +/ lies 5.5 kcal above H/sub 2/CO/sup +/. Zero-point vibrational energy corrections do not change this H/sub 2/CO/sup +/--HCOH/sup +/ separation. Similarly cis-HCOH/sup +/ is predicted to lie 4.1 kcal above the trans isomer, and the barrier to rotation between the two HCOH/sup +/ isomers is approx.18 kcal. The barrier to H/sub 2/CO/sup +/..-->..HCOH/sup +/ rearrangement is predicted to be 49.0 kcal, or 44.4 kcal after correction for zero-point vibrational energies is made. The relationship between this cationic 1,2-hydrogen shift and the corresponding neutral rearrangement is discussed in terms of qualitative molecular orbital theory.
- Research Organization:
- Department of Chemistry and Institute for Theoretical Chemistry, University of Texas, Austin, Texas 78712
- OSTI ID:
- 6734013
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 74:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FORMALDEHYDE
ISOMERIZATION
STEREOCHEMISTRY
HYDROXYL RADICALS
CATIONS
CONFIGURATION INTERACTION
GEOMETRY
MOLECULAR STRUCTURE
RADICALS
SELF-CONSISTENT FIELD
VIBRATIONAL STATES
ALDEHYDES
CHARGED PARTICLES
CHEMICAL REACTIONS
ENERGY LEVELS
EXCITED STATES
IONS
MATHEMATICS
ORGANIC COMPOUNDS
640300* - Atomic
Molecular & Chemical Physics